Geochemistry and genetic conditions of primary boninite magmas from the Ogasawara Archipelago and Guam Island-an insight from Cr spinel hosted melt inclusions

Abstract

How suboceanic mantle evolves into subarc mantle with the progress of a subduction zone is a fundamental question to understand the processes of subduction initiation and arc development. Primary arc magmas provide critical information to understand thermal and chemical structures of subarc mantle. We present geochemical characteristics of and genetic conditions of primary boninite magmas during the early stage of the Izu-Ogasawara-Mariana arc establishment (48-44 Ma), based on boninitic melt inclusions in chromian spinel from the Ogasawara Archipelago and Guam Island.